A regioselective cycloaddition between 3-dimethyl-4-(phenylsulfonyl)-4
H-furo[3,4-b]indole and 2-chloro-3,4-didehydropyridine is the key step
of a modification of Gribble's approach to ellipticines. The use of a
fluoride-promoted elimination for the generation of the pyridyne and
the control of the regioselectivity of the cycloaddition improve the y
ield of ellipticine by a factor of 3.